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Congruent phylogenies of most common small-subunit rRNA and dissimilatory sulfite reductase gene sequences retrieved from estuarine sediments.

ABSTRACT: The diversity of sulfate-reducing bacteria (SRB) in brackish sediment was investigated using small-subunit rRNA and dissimilatory sulfite reductase (DSR) gene clone libraries and cultivation. The phylogenetic affiliation of the most commonly retrieved clones for both genes was strikingly similar and produced Desulfosarcina variabilis-like sequences from the inoculum but Desulfomicrobium baculatum-like sequences from a high dilution in natural media. Related organisms were subsequently cultivated from the site. PCR bias appear to be limited (or very similar) for the two primersets and target genes. However, the DSR primers showed a much higher phylogenetic specificity. DSR gene analysis is thus a promising and specific approach for investigating SRB diversity in complex habitats.

SUBMITTER: Joulian C

PROVIDER: S-EPMC93019 | biostudies-literature | 2001 Jul

REPOSITORIES: biostudies-literature

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Congruent phylogenies of most common small-subunit rRNA and dissimilatory sulfite reductase gene sequences retrieved from estuarine sediments.

Joulian C C Ramsing N B NB Ingvorsen K K

Applied and environmental microbiology 20010701 7

The diversity of sulfate-reducing bacteria (SRB) in brackish sediment was investigated using small-subunit rRNA and dissimilatory sulfite reductase (DSR) gene clone libraries and cultivation. The phylogenetic affiliation of the most commonly retrieved clones for both genes was strikingly similar and produced Desulfosarcina variabilis-like sequences from the inoculum but Desulfomicrobium baculatum-like sequences from a high dilution in natural media. Related organisms were subsequently cultivated ...[more]

PMID: 11425760

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Project description:The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR). Here we provide the only direct observation of the major ((34)S/(32)S) and minor ((33)S/(32)S, (36)S/(32)S) sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB). Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in (34)S/(32)S (hereafter, [Formula: see text]) to be 15.3 ± 2‰, 2?. The accompanying minor isotope effect in (33)S, described as [Formula: see text], is calculated to be 0.5150 ± 0.0012, 2?. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3-0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in (34)?DsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of [Formula: see text] is similar to the median value of experimental observations compiled from all known published work, where (34)? r-p = 16.1‰ (r-p indicates reactant vs. product, n = 648). This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments ([Formula: see text] 17.3 ± 1.5‰, 2?) and in modern marine sediments ([Formula: see text] 17.3 ± 3.8‰). Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in modern and ancient environments.

Dataset Information

Congruent phylogenies of most common small-subunit rRNA and dissimilatory sulfite reductase gene sequences retrieved from estuarine sediments.

Publications

Congruent phylogenies of most common small-subunit rRNA and dissimilatory sulfite reductase gene sequences retrieved from estuarine sediments.

Similar Datasets

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